Moon trolls can occasionally happen when a troll is severely wounded by a lycanthrope. The lycanthropy disease is incompletely and imperfectly compatible with the troll’s metabolism, so the form the troll assumes at full moon is a huge, gnarled parody of the normal troll shape: misshapen and lumpish even by troll standards, with exaggerated claws and fangs. To exist in this form is painful, and the moon troll is often driven to extreme and bizarre acts of violence by sheer rage.